Production of workpieces from sheet metal unwound from a coil (for example, steel sheet) or from individual sheets or plates using a press or tool located in this press (for example, also follow-on tools) by punching, by permanent deformation, etc. is known. Here, providing tools with fasteners at the same time in production in the press is also known, by joining or insertion of the pertinent fastener into a prepared (punched) hole and by subsequent pressing of the fastener in the workpiece.
Fasteners are, among others, nuts or threaded nut pieces which for example have a circular cylindrical peripheral surface and which are provided with a collar on one front face, with which the respective nut fits into the prepared hole of the workpiece and is attached there by pressing.
To feed and attach especially nuts in workpieces a device for use in a press, for feeding fasteners, especially nuts, and attaching the fasteners in workpieces by pressing with a punching head has been suggested (P 43 40 642.4-14). This device consists essentially of a punching head which is provided on one or two antagonistic tool or press parts, and with the interposition of an insertion plunger causes joining of the respective fastener into the prepared hole of the workpiece and also with the cooperation of the other of the antagonistic tool and press parts causes subsequent attachment or fixing of the fastener in the workpiece by pressing, i.e., by permanent deformation of the material of the workpiece in the area of the hole. Furthermore, the known device has a rigid feed on which a loading and infeed means is provided and which, between this loading means and the punching head, forms a first rigid conveyor section which ends in the punching head or in a plunger channel formed there and which in the transportation and conveyance direction of the fastener adjoins a second, likewise rigid conveyor section, in the area of which the infeed means is provided at the transition between the two conveyor sections.
In this device the infeed means has an infeed element made as an infeed rocker which is normally in an active position, in which it elastically adjoins by one surface the last fastener in the first conveyor section and in this way prestress this fastener for movement in the direction of the punching head.
From this active position which is the normal position of the infeed rocker, the latter is moved by the motion of the antagonistic tool or press parts into an inactive position in which the infeed rocker is outside of the rigid feed, during each downstroke of the press shortly before reaching bottom dead center of the press stroke. At bottom dead center of the press stroke the fastener which is ready in the punching head is joined to the workpiece. During the subsequent upstroke of the press a new fastener from the second conveyor section is reloaded into the first conveyor section by the infeed rocker which returns to the normal position, i.e., to the active position.
Among others, the disadvantage here is that for reloading from the loading position into the "first" conveyor section only a relatively short time is available, specifically the time of a partial stroke of the press directly after bottom dead center.